Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 23
Sanskrit:
पुरा नारदशापेन वृक्षतां प्रापितौ मदात् ।नलकूवरमणिग्रीवाविति ख्यातौ श्रियान्वितौ ॥ २३ ॥
ITRANS:
purā nārada-śāpenavṛkṣatāṁ prāpitau madātnalakūvara-maṇigrīvāviti khyātau śriyānvitau
Translation:
In their former birth, these two sons, known as Nalakūvara and Maṇigrīva, were extremely opulent and fortunate. But because of pride and false prestige, they did not care about anyone, and thus Nārada Muni cursed them to become trees.